While doing some research the other day on firewalls, I came across (naturally) Wikipedia’s page on firewall comparisons. This page was actually exactly what I was looking for as it lays out some popular ‘personal’ and commercial options side by side.

Outside what I was looking for, you can see the Windows firewall actually compares quite nicely on the most important functionality, especially the one included with Windows Vista. The firewalls most of you may be interested in (the personal variety) are included at the top with, unfortunately, only limited data. For more detailed information on personal firewalls, check out this page. On the personal firewalls page, you can find links to reviews which can help if you are looking a for a firewall on your PC.